Working memory, the process of actively maintaining a representation of information for a brief period of time so that it is available for use, is a fundamental component of many aspects of higher cognitive processing. Working memory is necessary for analytical reasoning and vocabulary acquisition and appears to be highly correlated with IQ. Millions of people with conditions including HIV infection, attention-deficit hyperactivity disorder, Parkinson's disease, and schizophrenia, suffer from disruptions of working memory. Working memory is clearly an important cognitive function that appears to be susceptible to disruption in a wide range of diseases. Prefrontal cortex is thought to be critical to working memory function, but little is known about the specific neural mechanism of working memory. As part of a long range goal to improve our understanding of the role of prefrontal cortex in encoding, maintaining, and manipulating information, the goal of this particular project is to ascertain how different types of information are organized within the human prefrontal cortex. Using functional magnetic resonance imaging, three specific aims will be pursued. First, this project will examine the neural systems involved in maintaining information about different types of objects and the degree to which these neural systems are distinct from those involved in maintaining information about spatial locations. Second, this project will examine the degree to which the neural systems for maintenance of object and verbal information are distinct. Finally, the project will examine the neural mechanisms involved in integrating and maintaining multiple types of information in a coherent representation of the world. The proposed project will significantly advance our understanding of how the prefrontal cortex organizes different types of information and the role of prefrontal cortex in working memory. This will improve our understanding of those conditions in which prefrontal function is disrupted, and advance the goal of creating effective, targeted therapeutic strategies to treat or prevent the loss of working memory function.